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TUNING IN A Hearing Aid For COMTek by Harold Ort, N2RLL In what can only be described as yet another Corporate Big turning a deaf ear to what the rest of the world is hearing, COMTek and the City of Manassas Virginia, continue their campaign of ignorance of the facts. And I mean verifiable facts that clearly point to their BPL (Broadband Over Powerline) system as the continuing generator of interference so great that you practically don’t need a radio to hear it! But COMTek isn’t listening anyway. A recent ARRL Letter points to “flaws in Manassas BPL interference report,” and has “again demanded that the FCC shut down the system until the interference problems are solved.” So far, though, there has been no official response from the FCC. I suspect the Commission, in its bureaucratic mindset—thinks that it has responded appropriately. It has not.
Interference is so bad and the Commission’s
non-response so lacking that the League in its most recent 10-page letter
called the situation a “…tortured history of interference complaints
involving the BPL system.” The COMTek BPL network in Manassas is the first commercial deployment of BPL in the nation to use a city-wide electricity grid to provide homes and businesses with direct “plug in” broadband access through electric sockets, rather than over dial-up phone connections, DSL, or cable. Going back to 2004, licensed radio operators have demonstrated—as has the ARRL—that the COMTek BPL interference is the source of major interference to the HF bands, and yet for reasons only known to the FCC, the Commission hasn’t held COMTek’s feet to the fire. I suppose it’s a lot easier to bust a pirate radio operator or track down wayward illegal 10-meter operators driving the nation’s interstates than it is to drive a few miles to Manassas, listen to the interference firsthand, and enforce the very simple Part 15 rules.
In a letter to two FCC officials dated April
14, 2006, ARRL General Counsel Christopher D. Imlay, W3KD, concluded:
To read the entire article, subscribe to INFOCENTRAL News, Trends, And Short Takes by Harold Ort, N2RLL, Editor, and D. Prabakaran
Australia handed over a check for 2,181,000
Vanuatu vatu (U.S. $20,364) to General Manager of Vanuatu Broadcasting and
Television Corporation Jonas Cullwick. The infusion was made possible
through AusAID funding and will be used to replace two studio transmitter
links that transmit shortwave and mediumwave programs from the main studio
to the Emten Lagoon transmitter site. This transmission has not been
operational since May 2005, and Radio Vanuatu has had to use alternative
FM transmissions to enable shortwave and mediumwave to be broadcast to the
outer islands.
A report by Indonesia’s Antara News Agency
says that state radio broadcaster Radio Republik Indonesia (RRI) has been
conducting trial news bulletins in 11 international languages in an effort
to enable foreigners in Indonesia to obtain factual and accurate
information. According to RRI Director Parni Hadi, the trial broadcasts
have been in Arabic, English, French, German, Indonesian, Japanese,
Korean, Malaysian, Mandarin, Spanish, and Thai. The report says that RRI
also plans to use Russian and Italian in the near future.
Pakistan Broadcasting Corporation (PBC)
External Services has begun an English Service to Pakistanis residing in
Western Europe. The time of broadcast is 0730 to 0830 UTC and will be
beamed on 15100, 17835 kHz. With the introduction of the service, the
number of external services of PBC will increase to 17 languages. The
broadcaster is already broadcasting in Arabic, Bangla, Chinese, Dari,
English (targeting Eastern India), Gujarati, Hindi, Hazargi, Pushto,
Persian, Turkish, Russian, Nepali, and Sinhalese.
To read the entire article, subscribe to
“The Most Important...
The Story of Alessandro Fabbri and Radio Station NBD by Richard Moseson, W2VU, Editor CQ You’ve probably never heard of him, but according to the U.S. Navy, Allesandro Fabbri ran “the most important and most efficient” radio station in the world during and after World War I from a cliff top location in what is today Acadia National Park in Maine. If you’re one of the three million people a year who visit Acadia National Park, chances are you’ll take a drive along the Park Loop Road, perhaps stopping at Thunder Hole or Sand Beach. Just past Otter Cliffs, chances are you’ll see a small sign that reads “Fabbri Memorial.” And chances are you’ll keep on going. But if you do happen to pull off the road, manage to pull yourself away from the magnificent view off the top of the cliffs (Photo A) and make your way over to a tiny grove of spruce trees on the “back” side of the parking lot. There you’ll find a big rock (Photo B) containing a fading plaque to a man and a radio station that played a central role not only in early radio history but also in the outcome of World War I.
The plaque honors the memory of “Allesandro
Fabbri, Lieutenant, U.S.N.R.F.” (Photo C) and the Naval radio station at
that location, which he commanded during World War I. It’s described on
the plaque (and on Fabbri’s Navy Cross citation) as “the most important
and most efficient station in the world,” yet most of us have never heard
of Allesandro Fabbri nor his radio station.
The book that was my primary source of
information about the radio station, The Fabulous Radio NBD, by Brandon
Wentworth1, described Fabbri only as “a well-to-do socialite and yachtsman
who spent his summers at Bar Harbor” and having “devoted much of his time
to scientific endeavors, one of which was experimenting in wireless
telegraphy. It became his principal hobby.” When the federal government
started licensing amateur stations in 1912, the book says, Fabbri received
the callsign 1AJ, the tenth license issued in the first call district.
To read the entire article, subscribe to BROADCAST TECHNOLOGY FM/TV DXing: What Can You Get? by Bruce A. Conti
Many of us are into hearing shortwave signals from around the world or local and regional scanner action. But those FM and TV signals that normally reach a distance of about 60 miles often surprise even seasoned DXers. Actual standard coverage area will vary depending upon transmitter and receiver antenna height as well as terrain. This is because local FM/TV signals are limited by line of sight. Unlike AM or shortwave, there is no groundwave and “skip” of FM/TV under normal conditions.
FM/TV transmitting antennas are usually
located atop mountains, skyscrapers, and tall towers to increase distance
to the horizon, thereby increasing line-of-sight coverage area. (The
world’s tallest man-made broadcasting structure is the KVLY TV 11, Fargo,
North Dakota antenna mast, which at 2,063 feet set the standard for the
maximum allowed per FAA regulations.) However, for every rule there is an
exception, and there are unusual atmospheric conditions that will “bend”
the line-of-sight rule. The two basic modes of long-distance FM/TV propagation are tropospheric ducting and sporadic-E (Es) skip. Both involve some form of bending or redirecting of signals back toward Earth. The troposphere basically consists of the entire lower level of the atmosphere where weather takes shape through the formation of clouds. Under normal circumstances temperature decreases as altitude increases. Tropospheric ducting is a local to regional phenomenon, producing reception typically in the range of 300 to 500 miles. It’s caused by an inverse temperature differential between the ground level and upper levels of the atmosphere where the air is actually warmer at a higher altitude. A frontal boundary where warm air overrides cold air below, a temperature inversion that traps ground fog in the valleys and smog over large cities, or an onshore flow of cool humid air that produces pea-soup fog are examples of conditions ripe for tropospheric ducting. These inverse temperature differentials can bend a signal much like a beam of light through a prism. As light passes from air into the prism, each frequency within the light beam is bent at a different angle, revealing the rainbow of colors. Similarly, as signals pass from one temperature zone to another, each frequency is bent at a slightly different angle. With continued bending, distant VHF and UHF signals are scattered or showered back toward the ground level well beyond the horizon.
To read the entire article, subscribe to First Ladies Of The Air A Special Tribute: In 1900 One Third Of The Telegraphers Were Women, But Who Was First? By R.B. Sturtevant, KD7KTS
We do not know, and probably never will, who
was the first woman to transmit over a “wireless set.” This is because
before 1912 nobody was licensing or keeping records of who was using radio
to communicate.
Among the first women of radio was Graynella
Packer who, after working at a shore station in Sanford, Florida, for two
years, shipped out aboard the steamship S.S. Mohawk. Credited with being
the first female wireless operator to go to sea, Packer served from
November 1910 until April 1911.
It was extremely difficult for a proper lady
to get the training needed to work as a wireless operator. Because most
ships, or houses for that matter, didn’t have AC current running
everywhere, she needed to learn about small engines that drove generators,
as well as the generators themselves. Morse was required, of course, as
was construction and maintenance of the set, the building of antennas (no
simple feat in that primitive day), the handling of atmospheric
electricity, and a myriad of other things we today take for granted.
To read the entire article, subscribe to WASHINGTON BEAT
by Richard Fisher, KI6SN Four Texas radio amateurs have been advised by the FCC to take an “ongoing dispute” off the air or face enforcement action. According to the American Radio Relay League’s ARRL Letter, Riley Hollingsworth, Special Counsel in the FCC Enforcement Bureau, in February sent warning letters to Luis A. Caraballo, N7PLC, and Sharon E. Millhouse, KC5PRX, both of Floresville, Texas; and to Thomas O. Caldwell, WD5GXH, and Gary Sheets, WD5FWP, both of San Antonio. Hollingsworth said the dispute has “led to allegations of slander and deliberate interference” on the amateur bands, as reported in the ARRL Letter.
“The Commission is not concerned with the
merits, or lack thereof, of any dispute between you or of how you settle
such disputes,” Hollingsworth wrote, “but any use of amateur frequencies
to carry on the dispute is contrary to Section 97.1 of the rules and will
lead to enforcement action against the licenses of each of you.” Sanctions could include license revocation or suspension as well as fines of up to $10,000, Hollingsworth warned. “We may also consider proceedings to restrict or remove the voice privileges of your licenses,” he said. “This is the last warning you will receive before enforcement action is initiated.”
In early April, Hollingsworth said he’d gotten
responses from all but one of the individuals who received his letters,
but only one reply was in writing. In a handwritten note, Sheets pledged
to amend his attitude and practices, the ARRL reported. Hollingsworth said
he was awaiting written responses from the other three recipients.
To read the entire article, subscribe to
RADIO RESOURCES
by Gordon West, WB6NOA While it’s pretty common knowledge that a VHF marine radio doesn’t have to be FCC licensed if used locally in U.S. waters (and no operator license is required either for domestic use of marine VHF), this “no license” operating authority does not mean that anything goes on the marine VHF 156-MHz band. The FCC is quick to prosecute marine VHF handheld users working their equipment on shore.
A year ago one prominent marine VHF
manufacturer was advertising handheld radios, sold in blister-pack pairs,
as ideal for “hunting and fishing.” The company soon changed its ad to
read, “…between fishermen aboard boats on the water!” And, except for the
relatively complicated and expensive process of licensing a marine VHF
shore station or marine utility station on shore, shore-side operators
were not allowed to carry their 25-watt marine VHF back to their lakeside
cabin to transmit from shore to ship. Let’s take a look at the band itself, and from there see what another manufacturer, Uniden, has done to help us out. The marine VHF radio band begins with VHF Channel 1“A” at 156.050 MHz and extends up to marine VHF channel 88“A” at 157.425 MHz. A 4.6-MHz up-duplex split around 162 MHz is authorized for public correspondence shore stations. VHF Channel 16 156.800 MHz, the worldwide distress channel, along with VHF channel 22“A” 157.100 MHz, works as a liaison channel between commercial and recreational vessels to U.S. Coast Guard stations. (The designator “A” on some marine VHF channels indicates U.S. operators using simplex on this frequency, rather than the 4.6-MHz duplex found in Europe. Any VHF marine channel without an “A” is simplex worldwide).
Uniden now bridges the shore-to-ship gap with
an FCC-approved 2.4-GHz wireless microphone which completely controls its
25-watt marine VHF radios equipped to offer “WHAM” (a wireless microphone
for Uniden Oceanus/Polaris marine radios), compatibility for
full-function, half-duplex, remote-control for Uniden marine radios.
To read the entire article, subscribe to HAM DISCOVERIES
Dirty, Rotten
Interference— by Kirk Kleinschmidt, NTŘZ Now that I live in a downtown commercial building, whenever I get on 6 meters and swing my pathetic little Yagi in a southeasterly direction—the most likely to produce DX on a hot summer day in Minnesota—I hear a deafening buzz on the sweet part of the band. It’s no doubt due to the ancient power line that’s only 10 feet away, at the same height as the Yagi, which is about 35 feet above the ground. Some insulator up or down that line is abuzz with dirt, an untimely crack, or whatever. Or maybe it’s the air conditioning unit atop the adjacent building. Whatever it is, it almost never lets up. At my QTH, 6 meters isn’t open all that much these days, and when it is, the locally generated noise is a real killer. I can take some small consolation in the fact that I’m not alone. Modern hams are surrounded by RF devices and electronic gadgets that all seem to be waiting to pounce when it comes to radio interference. And all that stuff doesn’t even begin to include the somewhat humorous fact that, as hams, we even interfere with ourselves!
Most interference issues can be solved or
minimized. Running low power is an excellent first step if you’re
interfering with other electronic stuff. If interference is really ruining
your day, check out a recent edition of The ARRL RFI Book. This BIG
reference is a comprehensive resource for fixing every imaginable
interference problem in your home or mobile shack. Check your local
library or pay the few bucks required to get your own copy. You’ll use it
during your entire ham radio career (fortunately or otherwise,
interference doesn’t change too much, and neither do the techniques
required to resolve interference issues).
When interference rears its ugly head, who’s
to blame, anyway? And who’s responsible for cleaning up the mess? The
answers are varied. Before we examine specific solutions, let’s look a few
interesting RFI facts.
To read the entire article, subscribe to REACT IN ACTION Hitting The Road? by Ron McCracken, KG4CVL / WPZX486 Travel time is nearing its peak for another summer. Planning a road trip? Include a radio, or three, as you pack. Check your radio gear early to ensure reliable comms when you do hit the road. Your radios can make travel a lot more fun, and a lot safer, too. Remember, your cell phone is really a radio, and therefore behaves just like one. That means it can be just as helpful, and just as ornery as any other radio.
Also, your trusty CB can prove invaluable as a
source of critical information. I just returned from a road trip, and
believe me, I know. Listening to those professional drivers in their
18-wheelers on Channel 19 can keep you out of a whole lot of trouble. If
anything does happen, that same CB can get help to you , too.
Your scanner radio can also bring a lot of
enjoyment as you monitor boating, aircraft, and other comms along your
way. If you have room, slip it in somewhere for some relaxing fun on your
journey. Whatever the radio, if you run into trouble, you will be the key player in getting help. REACT volunteers and police dispatchers must depend entirely on your radio skills. Often, they can hear calls but a caller cannot hear their replies. One California REACT Team reported a 94-percent failure rate among calls for that very reason. But every one of them would have succeeded had the radio operator only known how to use the radio skillfully.
You need to broadcast repeatedly WHERE exactly
you’re located. Once REACT or police monitors hear that, help can be on
the way. Include the state, road, travel direction, nearest town,
crossroad, landmarks, etc. Keep each broadcast the same. Help the monitors
as much as you can by pinpointing your location. It is critical. On a cell
phone, this is the first information you utter to dispatchers. Then, even
if the call “drops” police can still send aid.
To read the entire article, subscribe to HOMELAND SECURITY
Putting
Personal Security by Rich Arland, K7SZ In writing the “Homeland Security” column I have a degree of latitude in the subject matter I present each month. Since I became intensely interested in military communications (MilComm) equipment, I outlined how a concerned emergency communications (EmComm) volunteer and/or serious radio hobbyist could press some of these older military radios into service on the ham bands to fulfill EmComm requirements under specific circumstances. In the past, I’ve also discussed various antennas and their construction and use, along with state-of-the-art comm gear needed for today’s EmComm environment. We’ve even talked about computers and computer (especially wireless fidelity or Wi-Fi) security.
This month’s column we’ll look at another type
of security, outlining how you can be much more conscious of your personal
security in your daily life. Personal security should be at the top of
your list. If you don’t feel “secure” in your daily life then you won’t
act “secure,” and you’ll be taking valuable mental resources away from
your job performance. This is not a good thing. Therefore, I’ll present a
few ideas on how you can become more proactive in your personal security
and get some much-needed peace of mind on a day-to-day basis.
One of the fastest growing crimes today is
identity theft. It’s nearly impossible for the perpetrator of the crime to
get caught in most cases, as unscrupulous individuals worm their way into
your personal and private life and use your credit cards, charge accounts,
bank accounts, etc., for their own pleasure and gain. Identity theft is a
big business on the street and, for the most part, very safe for those
individuals who would penetrate your inner life and steal your identity.
We’re going to cover some things you can do to protect yourself from
identity theft and keep your private life, well…private!
Believe it or not, your old bank statements,
credit card statements, financial records, personal records, etc., are
very easily intercepted on their way to the landfill by anyone with the
time and talent to rifle through your garbage (called “dumpster-diving” in
the trade), grab the paperwork, and piece all the paper trails together.
It sounds like a lot of work, but in reality, it’s very easy to do,
especially at night, the evening before the city trash pickup.
To read the entire article, subscribe to
Radio In The Rum
War
It was controversial from the very beginning,
“something the women snuck through while the boys were over in Europe
fighting for Democracy.” But, of course, no women ever voted for
Prohibition. It was the 18th Amendment and Women’s Suffrage was the 19th,
passed in 1920. But in 1919, when The Volstead Act was finally ratified,
everyone was sure that the “Noble Experiment” was going to succeed—or
fail. The Coast Guard had one of the hardest jobs. With no increase in budget and a force of only about 4,000 people and 75 vessels, it had to patrol 12,000 miles of American seacoast, including numberless bays, coves, bayous, rivers, inlets, ports, and beaches to make sure nobody landed any illegal spirits. It also had to keep up the high standard of lifesaving, aids to navigation, tariff collection, and other types of smuggling controls that it had established over its proud history. The Coast Guard brass also knew that the last time the U.S. coast had been embargoed was during the Civil War when the Union blockaded the Confederacy with more ships and manpower then was available during Prohibition. That had been a much smaller job and by no means a success. Nevertheless, the attitude of the Coast Guard during this period was expressed by their Commandant, Rear Admiral Fredrick C. Billard: “The Coast Guard will not fail in the performance of this…task. You men are the last line of defense…”
The earliest official mention of the Coast
Guard’s work in reducing this illicit trade was in their 1921 fiscal
report. In June of that year the report cited that the Florida coast
patrol had been “particularly vigilant” and had made “hundreds of trips”
in support of the Bureau of Prohibition’s authorities and had seized
several vessels.
The basic plan for profitable ocean-going
rumrunner was worked out by one William S. McCoy. McCoy, a Florida yacht
builder and racer, went to Gloucester, Massachusetts, and bought a
90-foot-long sail-powered schooner with two auxiliary engines for
emergencies, a type known as a Gloucester Fisherman. He sailed to Nassau
and loaded her with 3,000 cases of liquor. Fifteen hundred cases went to
his backers in Savannah at $10 per case. In less than two weeks he had
sold the balance of his cargo for enough to almost cover his $20,000
investment and at no risk to himself. He simply sat outside the three-mile
limit of U.S. control and sold his liquor to anyone who would run out and
pick it up. Within a few months every major port on the East Coast had a
“Rum Row” with hundreds of ships sitting just outside the Coast Guard’s
jurisdiction selling booze as fast as they could to anyone with a small
boat that could make the three-mile trip, fast.
To read the entire article, subscribe to
Report: Survey Results
We’re back with another few months’ worth of
your survey responses. Again, a special thanks for everyone for taking the
time to complete the cards, pay the postage, and wait for me to report
back to you! Yes, CW is indeed digital. A while back we asked shortwave listeners if they were interested in monitoring digital comms. Out of the 66 responses we received, two—hams nonetheless—asked if we knew what we were talking about by including CW in the list of digital modes. CW meets all the criteria for digital communications. It’s spectrum efficient, the information is transmitted as a standardized code (Morse), and it’s decoded at the receiving end. It can also be sent high speed. So now that our little trivia tidbit is out of the way, about one-third of you said you were interested in monitoring digital comms, while only about one-sixth said you were not. And CW is still the favorite digital mode, with about 25 percent of you weighing in for in its favor.
Nearly one-third of the respondents said they
didn’t know what was needed to receive those transmissions. Since we took
that survey, we’ve discussed the topic numerous times—both in the “Utility
Communications Digest” and “Computer-Assisted Radio Monitoring” columns—so
it’s our hope that when we ask this question again in the near future
there’ll be a heightened interest in and understanding of monitoring the
digital modes.
Surprisingly, about 42 percent of you reported
that although you’re a ham you currently don’t use the digital modes,
while about 15 percent said you did. Even less reported “sometimes” using
the digital modes, and about seven percent said you weren’t interested in
digital, preferring voice contacts over digital. The same number of folks
reported not having a computer in the shack!
To read the entire article, subscribe to
TECH SHOWCASE by Peter Bertini In the course of a pleasant chat with Harold after his appearance as a guest speaker at my local radio club, he offered me a chance try out a mobile HF antenna for a possible Pop’Comm review. Mobile ham radio HF operation was something I hadn’t experienced, so I accepted Harold’s offer on the spot! He returned from his car with the Shorty I screwdriver antenna, one of four mobile HF antennas products manufactured by Larry’s Antennas LLC1. I wasn’t expecting what he handed over; the antenna was hefty! Indeed, it was built like a Sherman tank!
The heart of the antenna is shown in Photo A.
What you get with your order is the antenna, mounting post, some hardware,
along with some cabling, and a reversing switch that lets you remotely
tune the antenna from the driver’s seat in the vehicle. What you need to
provide is a stainless steel whip and a means to securely the mount the
antenna. Maybe I’m getting ahead of myself here, and perhaps many of you are wondering what the heck a screwdriver antenna is, so let’s backtrack a bit.
Hams operating HF mobile (using ham bands
between 160 and 30 MHz) face some interesting challenges, and the
selecting the proper antenna is at the top of the list. For instance, a
100-inch whip will work as a very efficient quarterwave radiator on 10
meters, but you’d need a whip nearly 70 feet tall for 80 meters (3.5 MHz)!
Hams often used single band antennas, which required retuning to move to a
new portion of a band, or possibly even changing of loading coils
(inductors), whips, or some other form of manual intervention when
changing bands or moving to another frequency.
One way to operate a short antenna at a lower
frequency is to use a loading coil at the base of the antenna to lower its
resonant frequency. Some form of antenna loading was needed to limit the
mobile antenna height to less than 13 feet 6 inches, the legal height
limit in most states. Many mobile HF antennas use a large coil with
movable jumper to allow operating on several bands by manually moving the
tap point position on the coil to tune the antenna.
To read the entire article, subscribe to SCANTECH
Looking For New Frequencies? by Ken Reiss Finding new frequency information can be quite a chore. If you’re just getting started with scanning, however, you’re pretty well served by traditional frequency lists and Internet sites. Get familiar with all that these publications and websites have to offer. See if any of your local RadioShack employees have an interest in scanning, or check to see if there’s a local website. This could lead you to a wealth of information and save you a ton of work.
After you get a bit more experience with
scanning, though, you’ll begin to learn the details of the departments
you’re monitoring. You may also find additional services you didn’t think
you were interested in, but turned out to be quite entertaining. As you
do, you can begin to develop a band plan for your area, meaning what’s
used and by whom. It can be very helpful and informative to make a list of
every possible channel on a band and plug in the information you already
know. Now you can see how many “holes” there are in your knowledge. Once you’ve completed your list, or band plan, you can begin searching for unknowns with some confidence that you can correctly identify the intercepted signal, whether it’s a new frequency for you or just one you’d forgotten about.
Even without reading the rest of this article,
if you only take this suggestion and create lists, you’ll be way ahead of
most scanner enthusiasts and have much information to share with your
local club. Take the time to catalog what you know and what you don’t
know. Look at the channel listings in the back of Police Call and see just
how many channels there might be near you. How many can you identify in
your area?
Searching for new frequencies isn’t easy. Not
only is it time consuming, but figuring out what’s new versus what you
already know about isn’t exactly fun. On top of that, there’s the feeling
(or reality) that you’re missing something good on the frequencies you’d
normally be listening to, instead of “wasting” your time searching.
To read the entire article, subscribe to THE PROPAGATION CORNER
Powerful
Computer Tools To The Rescue For by Tomas Hood, NW7US Several months ago we started to explore the question, “When will good propagation occur?” Last month, we took a look at radio propagation analysis and forecasting tools, specifically ACE-HF (<www.acehf.com>). These tools help you unlock the science of radio propagation at the high frequencies.
Because of the mathematics involved, and the
vast amount of data that must be analyzed when analyzing and forecasting
radio signal propagation via the various ionospheric layers, you need more
than a pad of paper and a quick mind. Sophisticated programs that are
dedicated to the task are better suited to helping make the job more
approachable. With powerful computers available for reasonable prices, and
with affordable tools like WinCAP Wizard (www.taborsoft.com/) and ACE-HF,
any radio hobbyist can begin to make sense of all the factors that play a
role in radio communications on HF. This month, let’s dive into the VOACAP
model (<www.greg-hand.com/hfwin32.html>),
and specifically, the “reliability factor.” Whether you’re a ham or a shortwave listener, anyone who has listened on the HF shortwave bands knows how variable the ionosphere can be. Even without considering the other system factors of transmitter power, receiver sensitivity, noise, frequency, and so forth, the varying ionosphere is always with us, creating ever-changing propagation conditions that can make our DX hunting, or evening listening to a favorite station, a challenging experience. When we listen on HF radio and hear those elusive signals coming and going, chances are that the changing ionosphere is the cause. Most of the time, HF signals are stronger at night and become weaker during the daytime. Those diurnal effects are easy to understand because when the sun shines on the upper atmosphere, more of the gaseous atoms are converted to ions, and those charged particles multiply and expand the ionosphere to lower altitudes. At night sunlight is gone, so the masses of charged particles tend to dissipate and the ionosphere’s reflection height rises. But even when a radio circuit is entirely in daytime or nighttime, the signals still vary because the ionosphere is not uniform. I’ve never seen the ionosphere, but I suspect it would look like undulating cloud layers—and here in the Seattle area I’ve seen lots of those!
With all that going on, how in the world do we
answer that old question, “When will good propagation occur?” The solution
is to use a propagation prediction program. Modern HF propagation models
assume that HF signals “bounce” off a reflection layer of the ionosphere,
and models like ACE-HF and VOACAP include elaborate ionospheric profiles
that describe electron and ion density as a function of height. The
profiles vary with day and night, and are applied by the model according
to each circuit’s geometry. A long circuit may have several ionospheric
reflection points (usually called control points), and the profiles may be
different at each point. It takes a sophisticated computer model to keep
track of all that.
To read the entire article, subscribe to COMPUTER–ASSISTED RADIO MONITORING
Digital Signal
Processing—Part III by Joe Cooper As I pointed out in last month’s column on digital signal processing (DSP), the theory behind today’s “modern” technology is far from new. In fact, today’s electronic DSP technology has its origins in the very early days of telegraphy. Remember, telegraphy (the original digital mode) was first employed as a purely visual means of communications, using various systems of semaphores, which could employ arms, flags, suspended balls, or sign boards. This medium of visual communication was a vast improvement over earlier systems such as couriers on foot or horseback, but the signal (the visual images of the semaphores) could be interfered with by smoke, fog, rain, or nighttime, thus losing the message (or intelligence). Just as today’s radio signals can be interfered with by noise (static, electrical discharge, or lightning strikes), or fading (disturbances in the ionosphere), those visual telegraph “signals” could encounter their own form of noise with visual interference. One can argue that the act of converting a visual telegraphic signal into electrical pulses and transmitting them along metal wires was the first true application of electronic DSP technology. The use of such electrical signals over wires was indeed a successful strategy for reducing the amount of noise in a given signal and to ensure that the intelligence in a given signal was delivered. Electrical telegraphy is one of the most robust forms ever developed for the transmission of information over a long distance and has profoundly influenced the development of today’s digital technology. Your computer, CD player, digital cell phone, HDTV, and a host of other devices are in a sense nothing more than glorified telegraph keys, wires, and sounders.
In the 1930s, thanks to a desire to
incorporate that robustness into the transmission of audio signals
(whether through wires or radio waves), the theoretical foundation of the
digital revolution was established. The major breakthrough came about when
a brilliant, but eccentric, English scientist attempted to build a machine
to communicate with the spirits of the dead, using a combination of
spiritualist ideas and scientific theory. In fact, he claimed that many of
his ideas for digital communications came from discussions with the spirit
of 19th-Century scientist Michael Faraday. In addition to conducting these
“collaborations,” he spent time trying to scientifically measure “moon
beams” and to communicate with an American Indian “spirit guide” named Red
Cloud.
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Radio Slovakia International
Gets A by Gerry L. Dexter A celebration of sorts is in order! It seems that Radio Slovakia International will keep on keepin’ on, at least through the rest of this year. The government came through with the necessary funds to keep the service alive. This appears to be one case in which listener feedback helped save the day. Reception reports and QSLs are wonderful and important but we should all be doing a lot more in the way of writing and e-mailing stations with comments about programs or to point out technical problems, rather than making ourselves heard only when a station is on the brink of disaster. You can reach Radio Slovakia International at englishsection@slovakradio.sk or through their website at www.rsi.sk or via regular mail at P.O. Box 55, 817 55 Bratislava, Slovakia.
Two new Bolivian stations have opened on
shortwave recently. Radio Logos in Santa Cruz is occupying 6165. Best
times to check for this one would be in the early, early hours, say around
its 1000 sign on. The other one is Radio San Rafael in San Rafael,
Cochabamba, on 5680 variable, operating from around 0945 to sign off at
2200 (sometimes to as late as 2240). Although it’s announcing as Radio San
Rafael, DXers in South America say it is a reactivation of La Voz del
Campesino, which was located in Sipe Sipe. If you’ve been trying to get a QSL out of the Voice of America lately and your efforts have brought only frustration, be patient. The person responsible for QSLs at the VOA passed away some months ago and it has taken a while to find a replacement. Now the QSL machinery seems operational again.
The Italian Radio Relay Service (IRRS), which
carries various independently produced radio programs, was once exclusive
to Milan, Italy, with something less than thunderous power. Now, after
several years on the air, it appears to also be using powerful
transmitters in Bulgaria; never mind that the timings are not conducive to
reception in much of North America. Frequencies used are 5775 and 5885.
One of their clients is Brother Stair and his Overcomer Ministry.
To read the entire article, subscribe to SHANNON’S BROADCAST CLASSICS WMTR—A Model AM In The Baby-Boomer Era ’Burbs by Shannon Huniwell “Not again!” I screamed with an exaggerated wave of my arms. As happens almost daily, my computer’s inbox had been newly peppered with eBay “item of interest” e-mails forwarded by dear old Dad, the original, genuine AM & FM radio nut. This time his message simply promised, “Hey Kiddo, Get this stuff, and I’ll give you some neat information about the New Jersey station noted in the picture. Love, Pop.” Clicking on the indicated link switched my screen to a cute image of a little boy dressed in a cardboard microphone costume. The youngster wore headphones, had been subjected to a dollop of lipstick on his nose (perhaps to signify a glowing audio tube), and was crowned with a crude rendition of a self-supporting broadcast tower. Apparently, though, nobody else was as impressed with the photo. My opening bid of under $10 remained the sole offer through the entire weeklong auction. Almost immediately after winning the bid, Dad e-mailed me a story outline and reminder to “fire off a check ASAP so that the seller doesn’t have a chance to misplace the valuable photographic support documentation for the pioneer suburban radio article.” Honestly, sometimes I wonder why the Pop’ Comm management doesn’t just hire my father to ghostwrite this column! When the eBay vendor’s photo package arrived, I quickly discovered that few pictures in the deal had anything to do with radio history. In fact, the water-stained contents, which according to fine print from the seller had come from a yard sale back in the ’80s, represented a mundane, bottom-of-the-barrel potpourri of one N. L. Silverstein, a Morristown, New Jersey photographer. My heart sank as I shuffled through the stack of relatively uninteresting shots, mostly depicting portly bald guys wearing wide ties and smiling for the camera during some long-forgotten dinner meeting. “Annual Police Benevolent Association of Morris County at Dover Farms, Dover, NJ. 1949,” was penciled on the back of about a dozen yellowed photos. One after another looked pretty much the same, except for different people in the group having their eyes closed, or with distracting glare from the flashbulb reflecting off a piece of silverware. Finally, the 8 x 10 glossy of the radio kid appeared at the end of this pile. Stuck to it via static electricity, were three small negatives and a related newspaper piece describing announcers captured in the foggy black and white reverse images.
Except for the picture of the child in the mic
suit, none of it added up to enough for a broadcasting history article. I
sure hoped my father could make good on his promise to “turn the photos
into a 5000-watt story.”
To read the entire article, subscribe to LOOSE CONNECTION Lots Of Buffet….But No SSB by Bill Price, N3AVY Spring has sprung, the grass has riz, and Cowfield County is where Norm is. Or was. Norm’s last visit was so brief that we just met in a supermarket parking lot off the infamous Washington, D.C. “beltway,” where we transferred some ham radio gear from his car to my pickup. With the way we looked and the amount of junk we carried with us, we really had to work hard to appear as if we were not transferring stolen goods (which I really think several other groups of people were doing nearby). This trip was different. This time, Norm got to stay for almost three days. He had talked to me about the possibility of getting a new dog, another Spaniel, just like Chump, his never-to-be-forgotten silent-paw friend from our days together in the frozen tundra. Unfortunately, this adoption didn’t work out, and Norm must wait a little longer until he finds Chump II.
Norm said he had a coupon for some free nights
at a motel, but I really think it was fear that my pet rats would crawl on
him during the night that kept him from staying at the house with me. I
assured him I’d close their cage doors and not give them free run of the
spare room while he was there, but he just smiled and said, “That’s okay.
I’ve gotta use up these free coupons or they’ll expire.” I still don’t
think he had any coupons. After we did a lot of reminiscing about some people we had worked for, and worked with, and known over the years, he headed off to his motel. I told him I’d meet him and take him for an all-you-can-eat breakfast buffet the next morning. He said he really didn’t eat enough to justify a buffet, but reconsidered and said it would be worth it just to watch me eat. I didn’t let him down. This time, I knew we would have to put up an antenna, and even if I never worked another soul, whether on sideband or otherwise, I would have regular QSOs with Norm. As much as I dislike telephones (or microphones) and have come to love e-mail, Norm is not an e-mailer, and I have promised to become a sidebander, even if only with him.
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